Acetylene torch questions


Hi all,

I have been plugging away in my garage today making ingots to use in my class rolling mill. Today I was running the torch for awhile and the pressure seems to still be fairly high, but the torch sputtered and started dripping liquid acetylene (at least that's what I think it I've shut off the valves and stopped using the torch. My question is, why would the torch start to do that? Is there a minimum pressure that you have to have for the torch to work? (I think I read 75psi min, but it seems to still be at 200psi)... Does the gas go bad after awhile? The tank hasn't been used in about 8 months. Do I just need to let the tank sit for awhile to let the gas expand again? The valves seemed cold to the touch, so I'm wondering if it's like my mapp gas torches that stop functioning when they get cold...

Any help would be appreciated.

marilyn's picture

I have had a Presto Lite

I have had a Presto Lite air/acetylene torch for more than twenty years and never had this happen. Are you using oxygen with the acetylene .? Has the tank been kept vertical?


Rich Waugh's picture



It sounds like you may be drawing off the acetone that the acetylene is dissolved in, and that can both damage your torch and cause an explosion. Shut off the cylinder, disconnect the regulator, and take everything to your gas/welding supplier and have it all checked out.


wagin's picture

Sounds like the acty

Sounds like the acty cylinder was stored horizontal. If this is the case, placing the cylinder up-right for a day or so should correct the problem. Otherwise, I would return the cylinder to your gas supplier.

visitor's picture

acetone bleed off

what is happening is that you are using gas faster than it can evaporate from the acetone. This happens when you use 1, a tank thats too small, 2 a tip thats too bigg,or 3 running too long at too high a flow rate. The solution is get a bigger tank, switch to mapp or propane gas, or manifold several tanks together. I have only rarely actualy seen this happen, but I use large tips on my torch, almost never run it for very long and when i do i manifold three tanks together and switch to liquid oxygen. Yes that is the next problem you'll run into ! The only time i have had that I have run into this was in cutting anvils and hammer dies from 4" 4140 plate! I have heard of the problem when using a large rosebud though.

visitor's picture

This is the right answer

1/7 of tank/hr from what I've read.

visitor's picture

acetone bleed off.

I'm new to this. Do you mean you can use propane in place of acetylene with an oxy/act regulators torch hookup?

Rich Waugh's picture

Visitor, For general heating


For general heating and cutting, you can use propane with oxygen, instead of oxy/acetylene, yes. You will need to get a different fuel gas regulator, as the acetylene regulator is designed to be used at up to about 14 psig outlet pressure and you will probably want over twice that much with propane. Also, the seals in an acetylene regulator may not tolerate propane well.

For cutting with oxy/propane you will need to get special propane cutting tips. These area 2-piece tip with internal mixing, specially designed for use with propane. Major name torches like Victor and Smith will accept the propane tips with no special adapters.

The other thing you must be aware of is your hose. The standard hose for acetylene is Type R, which is not suitable for propane. For propane you need Type T hose. It only costs a couple dollars more than the type R and can be used with both propane and acetylene should you decide you want to use acetylene for welding. You can't weld decently with propane, by the way.

Hope this clears things up for you.


visitor's picture

Propane pressure

Rich, what propane torches run on 28 p.s.i. or more? My biggest rosebud, 2" diameter head, handle 5' long only needs 15 p.s.i. propane, 60 p.s.i. oxy.
John Chritiansen

Rich Waugh's picture

John, I'm not aware of any


I'm not aware of any common oxy/fuel torches that run on more than 28 psig, although I have a couple of propane/air troches that run at pressures up to 50 psig. I use these, which are basically a big forge burner, for stationary heating of large pieces for welding pre-heat and the like. I wouldn't use the oxy/propane for that since the cost of the O2 would get excessive and I wouldn't be able to set the torch and walk away from it to do something else while it heats - that would be a good way to end up with a melted lump using oxy/fuel. :-)

Regardless, if you're using 15 psig pressure you would generally want a regulator that was sized so that this pressure fell in about the middle of the gauge scale. Most gauges are most accurate in the middle of their scales and considerable less accurate at the extremes. A 30 psi gauge would put 15 psi in the center of the dial where you could have some degree of faith that it was accurate.

The chief reason for not using an acetylene regulator for propane is, however, the possibility of seals that are not compatible with propane. While you could have the seals replaced with appropriate materials, it is probably cheaper to just get a propane regulator.


rusl's picture

Acetylene is dangerous!


Acetylene should only ever be used up to 15psi! The tank has a honeycomb and acetone liquid to allow for safe storage and a higher pressure inside the tank. For this reason it is unsafe to store Acetylene bottles horizontally. Acetylene above 30psi is liable to explode. It is highly volatile and unstable (which makes it great for welding)

Do NOT use that AO setup until you can be certain that the tank and fuel gas are safe. This may mean replacement or qualified serice. You are very fortunate there was no explosion!

OSHA standard, 1910.253(a)(2) says:

Maximum pressure. Under no condition shall acetylene be generated, piped (except in approved cylinder manifolds) or utilized at a pressure in excess of 15 psig (103 kPa gauge pressure) or 30 psia (206 kPa absolute). ... This requirement is not intended to apply to storage of acetylene dissolved in a suitable solvent in cylinders manufactured and maintained according to U.S. Department of Transportation requirements, or to acetylene for chemical use. The use of liquid acetylene shall be prohibited.